This invention relates to apparatus for processing a polychromatic optical image beam to produce electrical signals for displaying the image on a color television receiver.
The invention also provides improved apparatus for the home display of motion pictures on a standard color television receiver.
It is known in the art of color television to divide the image beam from a scene into sub-beams that are processed to produce signals responsive to the red, the green, and the blue constituents of the original beam. Often a further signal, responsive to the image brightness or luminance, is produced. The signals are selectively combined to produce, according to the National Television System Committee (NTSC) format, two chrominance signals termed an I signal and a Q signal, and a luminance, or Y, signal. These known practices are described for example in Color Television Fundamentals, 2nd Edition by Milton S. Kiver, McGraw-Hill Book Company; and in Chapter 25 of Electronic and Radio Engineering, 4th Edition, by Frederick E. Terman, McGraw-Hill Book Company, Inc.
U.S. Pat. No. 3,284,566 of James et al discloses a color television camera that employs four reflectors, two of which are dichroic, to divide an optical beam into three sub-beams which respectively are responsive to red light, to blue light and to luminance. Other color television cameras and signal generators are disclosed in U.S. Pat. No. 3,833,756 of Kumagi et al; U.S. Pat. No. 3,934,265 of Toms et al; U.S. Pat. Nos. 3,952,328 and 3,953,885 of Biber; and U.S. Pat. No. 3,506,778 of Gold et al.
Also of interest is the prior apparatus described in the commonly-assigned U.S. Pat. No. 4,151,560 issued Apr. 24, 1979 for "Apparatus And Method for Displaying Moving Film On A Television Receiver" of Michael Zinchuk; and the commonly-assigned U.S. Pat. No. 4,148,071 issued Apr. 3, 1979 for "Apparatus For Displaying Moving Film On A Television Receiver" of Michael Zinchuk.
Further, U.S. Pat. No. 3,497,283 of Law discloses an optical beam splitter for color television use which employs selective polarization changes to produce a luminance-responsive signal and three separate color signals. It is also known from U.S. Pat. No. 3,925,813 of Toyama et al to provide an optical beam splitter which employs two prisms with a combination of reflective and absorbent filters to produce two partial beams, one responsive to both a first color and to brightness, and the other responsive to two further colors. U.S. Pat. No. 3,704,061 of Travis discloses another optical splitter for producing three differently colored sub-beams from an incident beam and in which the splitter element employs a combination of three reflecting and absorbing optical filters. The following U.S. Patents disclose other optical beam-splitter arrangements for producing three separately-colored partial beams from a polychromatic beam: U.S. Pat. No. 3,202,039 of DeLang; U.S. Pat. No. 3,659,918 of Tan; U.S. Pat. No. 3,767,290 of Lang; U.S. Pat. No. 3,798,354 of Asou; U.S. Pat. No. 3,802,763 of Cook et al; and U.S. Pat. No. 4,035,836 of Miyaji.
This is an object of this invention to provide television-compatible apparatus for processing a polychromatic optical beam and which is characterized by simplicity and few signal-processing operations, and yet is capable of relatively high quality image display.
Another object of the invention is to provide an improved polychromatic image-processing optical beam splitter which has relatively simple optical structure and relatively low light loss, and hence which operates with relatively high efficiency. Further, the splitter is to be relatively compact and subject to relatively low cost manufacture.
It is also an object of the invention to provide improved apparatus for consumer use in the home to display motion pictures on a standard color television receiver.
Other objects of the invention will in part be obvious and will in part appear hereinafter.